SafiandClaude Opus 4.8
c50ffc2285
.docx/.xlsx are zip+XML containers parsed during a corpus scan with no size guard, so a few-KB zip-bomb could decompress to gigabytes and OOM-kill the process. Screen every office/PDF file before openpyxl/python-docx/pypdf touch it: an on-disk size cap, a total-uncompressed cap, and a compression-ratio check on the archive members. Files that exceed the caps are skipped (treated as empty) rather than parsed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
64 lines
2.5 KiB
Python
64 lines
2.5 KiB
Python
"""Resource-cap guards for parsing untrusted office/PDF files (F2).
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.docx/.xlsx are zip+XML containers; a few-KB zip-bomb can decompress to
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gigabytes and OOM-kill the process during a corpus scan. These tests verify the
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pre-parse screen rejects bombs before openpyxl/python-docx ever decompress them.
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"""
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import zipfile
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from graphify import detect
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def _write_zip(path, name, payload):
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with zipfile.ZipFile(path, "w", zipfile.ZIP_DEFLATED) as zf:
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zf.writestr(name, payload)
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def test_file_within_size_cap(tmp_path):
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f = tmp_path / "a.bin"
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f.write_bytes(b"x" * 1024)
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assert detect._file_within_size_cap(f) is True # within default cap
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assert detect._file_within_size_cap(f, cap=512) is False # over an explicit small cap
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assert detect._file_within_size_cap(tmp_path / "missing") is False
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def test_zip_ratio_bomb_rejected(tmp_path):
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"""A tiny file that expands far past the ratio threshold is rejected."""
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bomb = tmp_path / "bomb.xlsx"
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_write_zip(bomb, "xl/worksheets/sheet1.xml", b"0" * (5 * 1024 * 1024)) # 5 MiB of zeros -> tiny zip
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assert bomb.stat().st_size < 100 * 1024 # compressed to well under 100 KiB
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assert detect._zip_within_caps(bomb) is False
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def test_legit_zip_passes(tmp_path):
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ok = tmp_path / "ok.docx"
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_write_zip(ok, "word/document.xml", b"<xml>hello world</xml>" * 20)
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assert detect._zip_within_caps(ok) is True
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def test_non_zip_rejected(tmp_path):
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notzip = tmp_path / "fake.xlsx"
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notzip.write_bytes(b"this is not a zip file")
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assert detect._zip_within_caps(notzip) is False
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def test_converters_return_empty_for_bomb(tmp_path):
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"""The live converters bail out (return "") on a bomb before parsing."""
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for ext in (".docx", ".xlsx"):
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bomb = tmp_path / f"bomb{ext}"
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_write_zip(bomb, "x.xml", b"0" * (5 * 1024 * 1024))
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assert detect.docx_to_markdown(bomb) == ""
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assert detect.xlsx_to_markdown(bomb) == ""
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def test_pdf_over_cap_returns_empty(tmp_path, monkeypatch):
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"""A PDF larger than the raw cap is skipped before pypdf opens it."""
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big = tmp_path / "big.pdf"
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big.write_bytes(b"%PDF-1.4\n" + b"x" * 4096)
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# shrink the cap via the helper's default by patching the module constant and
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# calling through a wrapper that reads it fresh
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monkeypatch.setattr(detect, "_OFFICE_MAX_RAW_BYTES", 100)
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monkeypatch.setattr(detect, "_file_within_size_cap",
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lambda p, cap=100: p.stat().st_size <= cap if p.exists() else False)
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assert detect.extract_pdf_text(big) == ""
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